• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.251-254
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• 2001

In this paper, we analyzed the properties change of electric wire when the thermal stress was applied to NFR-8 and FR-PVC 600[V] wire. Messurement is made of the attenuation of a light beam by smoke accumulating with in a closed chamber due to nonflaming pyrolytic decomposition and flaming combustion. Results are expressed in terms of specific optical density which is derived from a geometrical factor and the measured optical density a measurement characteristic of the concentration of smoke. Referenced documents were ASTM E662 standard test method for specific Ds genalated by solid materials. The furnace control system shall maintain the required irradiance level under steady-state condition with the chamber door closed of $2.5{\pm}0.04[w/cm^{2}]$ for 20 min. According to the results of the smoke density analysis of NFR-8 and FR-PVC the highest decomposition flaming smoke density range of NFR-8 and FR-PVC were 25.2 to 37.5 and 51.1 respectively. Nonflaming smoke density range of NFR-8 and FR-PVC were 100.4 to 112.2 and 126.5 to 398.8. The amount of carbon monoxide generated was found to be much higher in FR-PVC decomposition than in NFR-8 due to incomplete combustion of FR-PVC which has high content of carbon in compound.

• Biomolecules & Therapeutics
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• 제17권1호
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• pp.25-31
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• 2009

Clusterin is a heterodimeric sulfated glycoprotein and plays a role in many different types of cancer as a cell survival factor and helps cancerous cells to evade stress-induced apoptosis. To investigate whether the regulation of clusterin expression is involved in the mechanism of anticancer agent, we studied the effect of tamoxifen on clusterin expression in human prostate cancer PC-3 cells. Treatment of PC-3 cells with tamoxifen reduced cellular proliferation. Western blot analyses showed that treatment with tamoxifen suppressed clusterin expression in a concentration-dependent manner. Transfection with clusterin siRNA plasmid showed that clusterin is required for PC-3 cell survival. We found that tamoxifen resulted in a rapid decrease in the phosphorylation of Akt on Ser473 leading to prevent kinase activity. Expression of myristoylated Akt prevented tamoxifen-mediated clusterin downregulation. Interestingly, MG132, a wellknown proteasome inhibitor also recovered clusterin expression suppressed by tamoxifen. These data indicate that clusterin expression may be regulated by activation of Akt and ubiquitin-proteasome pathway plays an important role in tamoxifen-mediated clusterin suppression.

• 한국자동차공학회논문집
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• 제19권3호
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• pp.1-8
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• 2011

Stainless steel sheets are widely used as the structure material for the railroad cars and the commercial vehicles. These kinds structures used stainless steel sheets are commonly fabricated by using the gas welding. Gas welding is very important and useful technology in fabrication of an railroad car and vehicles structure. However fatigue strength of the gas welded joints is considerably lower than parent metal due to stress concentration at the weldment, fatigue strength evaluation of gas welded joints are very important to evaluate the reliability and durability of railroad cars and to establish a criterion of long life fatigue design. In this paper, ${\Delta}-N_f$ curve were obtained by fatigue tests. Using these results, the accelerated life test (ALT) is conducted. From the experimental results, an acceleration model is derived and acceleration factors are estimated. So it is intended to obtain the useful information for the fatigue lifetime of plug and ring gas welded joints and data analysis by statistical reliability method, to save time and cost, and to develop optimum accelerated life prediction plans.

• 대한조선학회논문집
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• 제44권6호
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• pp.612-618
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• 2007

There are a lot of openings, holes and slots in ship structural members. It is not easy to solve the troubles around the openings adequately at the detail design stage, because there are a lot of concerning locations. There are not also clear design rules of classification societies and it is not possible to apply direct calculation for all the concerning members. Therefore, it is necessary to set up simplified approach such as a standard or guidance in order to decide the opening design quickly. For this study, guidance and regulations of each classification and several companies were surveyed. Grillage analysis and the refined mesh method were used to evaluate the strength around hole considering boundary condition and more detailed member arrangement. As a result, the standard for opening design was established and verified.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.251-254
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• 2001

In this paper, we analysed the properties change of electric wire when the thermal stress was applied to NFR-8 and FR-PVC [600] wire. Measurement is made of the attenuation of a light beam by smoke accumulating with in a closed chamber due to nonflamining pyrolytic decomposition and flaming combustion. Results are expressed in terms of specific optical density which is derived from a geometrical factor and the measured optical density a measurement characteristic of the concentration of smoke. Referenced documents were ASTM E662 standard test method for specific Ds generated by solid materials. The furnace control system shall maintain the required irradiance level under steady-state condition with the chamber door closed of 2.5${\pm}$0.04[w/$\textrm{cm}^2$] for 20 min. According to the results of the smoke density analysis of NFR-8 and FR-PVC the highest decomposition flaming smoke density range of NFR-8 and FR-PVC were 7.2 to 77.5 and 51.1 respectively. Nonflaming smoke density range of NFR-8 and FR-PVC were 100.4 to 112.2 and 126.5 to 398.8. The amount of carbon monoxide generated was found to be much higher in FR-PVC decomposition than in NFR-8 due to incomp1ete combustion of FR-PVC which has high content of carbon in compound.

• 대한기계학회논문집A
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• 제25권6호
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• pp.965-971
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• 2001

To estimate the reliability of 12Cr alloy steel, the material of turbine blade in the steam power plant, Its corrosion susceptibility and fatigue characteristics in NaCl and Na$_2$SO$_4$solution with the difference of concentration and temperature was investigated. The polarization tests recommended in ASTM G5 standard for corrosion susceptibility in the various corrosive solutions was estimated. It showed that the higher temperature, the faster corrosion rates and corrosion rates were the fastest in 3.5 wt.% NaCl and 1M Na$_2$SO$_4$solution. From these results, the degradation conditions were determined in distilled water, 3.5 wt.% NaCl and 1M Na$_2$SO$_4$solution at room temperature, 60$\^{C}$ and 90$\^{C}$ during 3, 6 and 9 months. Its surface had a few pits for long duration. But, it was not susceptible in sulfide and chloride condition of several temperatures. If the degraded 12Cr alloy steel and non-degraded one were compared with fatigue characteristics, Any differences were not found regardless of temperature and degradation period.

• Journal of Microbiology and Biotechnology
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• 제30권6호
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• pp.868-877
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• 2020

Bicarbonate has been considered as a better approach for supplying CO₂ to microalgae cells microenvironments than gas bubbling owing to cost-effectiveness and easy operation. However, the β-carotene production was too low in Dunaliella salina cultivated with bicarbonate in previous studies. Also, the difference in photosynthetic efficiency between these two carbon sources (bicarbonate and CO₂) has seldom been discussed. In this study, the culture conditions, including NaHCO₃, Ca²⁺, Mg²⁺ and microelement concentrations, were optimized when bicarbonate was used as carbon source. Under optimized condition, a maximum biomass concentration of 0.71 g/l and corresponding β-carotene content of 4.76% were obtained, with β-carotene yield of 32.0 mg/l, much higher than previous studies with NaHCO₃. Finally, these optimized conditions with bicarbonate were compared with CO₂ bubbling by online monitoring. There was a notable difference in F_v/F_m value between cultivations with bicarbonate and CO₂, but there was no difference in the F_v/F_m periodic changing patterns. This indicates that the high concentration of NaHCO₃ used in this study served as a stress factor for β-carotene accumulation, although high productivity of biomass was still obtained.

• 정신신체의학
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• 제28권2호
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• pp.177-184
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• 2020

연구목적 산후우울증은 일반적으로 산모의 10~15%에서 발병하는 질환으로 그 원인으로는 정신사회적인 요인과 산과적인 요인이 모두 관계 있다고 알려져 있다. 감염, 손상, 악성종양, 자가면역질환, 스트레스에 의해 면역체계가 자극되면 proinflammatory cytokine과 anti-inflammatory cytokine이 생성되고 분비된다고 알려져 있다. 본 연구에서는 산후우울증이 있는 경우 산후우울증이 없는 군에 비해 혈중 Transforming growth factor-β1(TGF-β1), Insulin-like growth factor-1 (IGF-1), β-Nerve growth factor (β-NGF), Interleukin-2 (IL-2), IL-4, IL-6, Tumor necrosis factor-α (TNF-α), Interferon-γ (IFN-γ)의 농도가 상승되어 있을 것이라 가정하고, 임산부에서의 우울증의 경과에 따라 cytokine의 농도의 변화를 알아보고자 한다. 방 법 본 연구는 총 104 명의 임산부와 60명의 임신을 하지 않은 정상 대조군을 대상으로 하였다. 우울 증상은 임신 24주, 출산 1주, 출산 6주에 에딘버러 산후 우울 척도(EPDS)를 사용하여 평가하였다. EPDS의 총 점수가 10 이상인 경우, 우울증상이 있는 것으로 판단하였으며 EPDS 점수 변화에 따라 임산부 정상대조군, 출산 후 우울-회복군, 출산 후 우울군 세 그룹으로 나누었다. 결 과 임신군과 비임신 정상대조군을 비교하였을 때 TGF-β1, IGF-1의 혈장 농도는 임신군에서 비임신 정상대조군보다 더 높았다(TGF-β1 ; p<0.01, IGF-1 ; p=0.026). 그러나 β-NGF, IL-2, IL-4, IL-6, IFN-γ, TNF-α는 비임신 여성대조군에 비해 임산부 정상대조군에서 그 농도가 낮게 측정되었다(β-NGF ; p=0.001, IL-2 ; p<0.01, IL-4 ; p<0.01, IL-6 ; p<0.01, IFN-γ ; p<0.01, TNF-α ; p<0.01) 임신 24주에 TGF-β1, IGF-1, β-NGF, IL-2, IL-4, IL-6, IFN-γ, TNF-α의 농도를 살펴보면 임산부 정상대조군, 출산 후 우울-회복군, 출산 후 우울군 세 군간에 유의한 차이가 없었으며 출산 6주에도 역시 유의한 차이가 관찰되지 않았다. 또한 임신 24주, 출산 6주에 시간에 따른 농도 차이를 비교해 보았을 때 세 군에서 모두 그 통계적으로 유의한 차이는 없었다. 결 론 본 연구는 비임신 정상대조군과 임신군간의 혈장 cytokine 농도에서 유의한 차이를 발견했으나 산후우울증군과 정상 임신대조군간의 혈장 cytokine 농도는 유의한 차이를 밝혀내지는 못했다.

• 한국전산구조공학회논문집
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• 제28권3호
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• pp.283-291
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• 2015

본 논문에서는 원통형 쉘에 부착된 노즐의 구조 건전성평가를 수행하고 그 결과를 비교하기 위해 2차원(2D)과 3차원(3D) 해석이 수행되었다. 현재 원자력 발전소에서 사용되는 3개의 노즐을 구조 건전성평가를 위해 선정하였고, 각각 노즐은 내부압력, 온도변화 및 외부하중을 받는다. 내부압력에 대한 2D 해석은 1.5이상의 계수 값을 이용하거나 응력집중 계수를 적용하여야 하고, 온도변화에 대한 2D와 3D 해석결과는 피복재의 유무와 상관없이 서로 거의 비슷하며, 외부하중에 대한 WRC Bulletin 297에 의한 해석결과는 3D 해석결과보다 더 보수적임을 확인할 수 있었다.

• 대한기계학회논문집A
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• 제21권1호
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• pp.93-103
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• 1997

Charpy V-notch impact tests were performed on the full-, half-and third-size specimens from two ferritic SA 508 Cl. 3 steels for nuclear pressure vessel. New normalization factors were proposed to predict the upper shelf energy(USE) and the ductile-brittle transition temperature(DBTT) of full-size specimens from the measured data on sub-size specimens. The factors for the USE and the DBTT are $(Bb^2/Kt); and; (Bb/R)^1/2/, $ respectively, where B the width, b the ligament size, $K_{t}$ the elastic stress concentration factor, and R the notch root radius. These correlations successfully estimated the USE and DBTT of the full-size specimens based on sub-size specimen data. In addition, the size effects were studied to develop the correlations among absorbed energy, lateral expansion(LE) and displacement. It was also found that the LE was able to be estimated from the displacement obtained by the instrumented impact test, and that the displacement would be used as a criterion for the toughness of the steels corresponding to change in their yield strength.h.